1. Field of Invention
The present invention relates to a breaker apparatus which fits a movable electrode with a pair of fixed electrodes and separates the movable electrode from the pair of fixed electrodes to thereby open and close a circuit.
2. Description of Related Art
In a breaker apparatus of this type, for example, there is known a breaker apparatus which is disclosed in JP-A-2000-235824. According to this breaker apparatus, a fixed-side housing, including a pair of mutually insulated fixed electrodes, is fitted with a movable-side housing including a movable electrode to thereby short-circuit a pair of fixed electrodes. By pulling a handle disposed on the movable-side housing, the movable-side housing is separated from the fixed-side housing to thereby remove the short-circuit between the pair of fixed electrodes.
However, in this breaker apparatus, when separating the movable-side housing, an operator holds the handle by hand and separates the movable-side housing at a stretch with all his or her strength. This means that, on the back surface side (on the opposite side to the fixed-side housing) of the movable-side housing, there is a relatively large operation space required in the fitting and separating direction of the two housings. Therefore, when sufficient operation space cannot be secured, for example, in a space within an engine room of an automobile, it is difficult to install the above-mentioned breaker apparatus.
To solve the above problem, the present applicants have proposed a breaker apparatus having the following structure. In this breaker apparatus, a driven pin is disposed in a fixed-side housing in a movable-side housing a drive member is disposed which is prevented from moving in the two-housing fitting direction but is allowed to move in a direction at right angles to the fitting direction. The drive member includes an inclined groove which is inclined with respect to the moving direction of the drive member. When the two housings are made to approach each other to thereby bring the driven pin into engagement with the entrance of the inclined groove and the drive member is moved from this engaged state, due to the engagement between the inclined groove and driven pin, the movable-side housing is pulled near to the fixed-side housing so that the two housings are fitted with each other. Also, when the drive member is moved from the fitted state in the opposite direction to the fitting direction, due to the engagement between the inclined groove and driven pin, the movable-side housing is separated from the fixed-side housing. In this manner, when removing the two housings from each other, by using a cam action due to the engagement between the inclined groove and driven pin, the movable-side housing can be separated from the fixed-side housing with a small operation force.
Further, in the present breaker apparatus, the fixed electrodes are disposed in an intermediate portion of a power circuit of an electric car and are used as a means to break the power circuit. In this structure,.when the movable electrode is suddenly removed from the fixed electrodes while the power circuit is electrically energized to thereby open the power circuit, there occurs an arc. In view of this, there can be expected the following structure: a relay circuit serving as switching means for opening and closing the power circuit, and a microswitch serving as a detect means which detects the movement of the drive member to thereby operate the relay circuit.
According to this structure, in a state where the two housings are fitted with each other and the fixed electrodes are fitted with the movable electrode (in a state where energization is permitted between the pair of fixed electrodes), the relay circuit executes its closing operation to thereby close the power circuit. When the movement of the drive member to separate the two housings from each other is started, just after the start of the movement of the drive member, the movement of the drive member is detected by the microswitch, and the relay circuit is allowed to execute its opening operation to thereby open the power circuit. When the movement of the drive member is moved further, the movable electrode is separated from the fixed electrodes and since the power circuit is already opened by the relay circuit, occurrence of the arc between the electrodes can be prevented.
However, between the start of the opening operation of the relay circuit and the time when the opening operation is completed and the energization of the power circuit stops, there exists a time lag (of the order of 150 msec.). Therefore, to prevent the occurrence of the arc, from the start of the opening operation of the relay circuit to the time when the fixed and movable electrodes are separated from each other, there is necessary the time that is longer than the above time lag.
Here, the moving operation of the drive member from the fitted state of the two housings (i.e., the closed state of the power circuit) to the time when the opening operation of the relay circuit is started and, after then, the fixed and movable electrodes are separated from each other is a linear-shaped one-action operation to be executed in a direction at right angles to the fitting direction of the two housings. Therefore, when the drive member is operated with great force, there is a fear that, although the opening operation of the relay circuit is not completed but the power circuit remains closed, the movable electrode can be removed from the fixed electrodes.
The present invention aims at eliminating the drawbacks found in the above-mentioned conventional breaker apparatus. Accordingly, it is an object of the invention to provide a breaker apparatus which can prevent the movable electrode from being separated from the fixed electrodes while a main circuit remains closed.
In attaining the above object, according to a first aspect of the invention, there is provided a breaker apparatus having a pair of fixed electrodes disposed in series in a main circuit to be opened and closed by switching means. The breaker apparatus also includes a movable electrode disposed in a movable-side housing that is fitted with and separated from the pair of fixed electrodes to thereby allow or prevent energization between the pair of fixed electrodes independently of the opening and closing operation of the switching means. The breaker apparatus further comprises a guide means for guiding a fixed-side housing, with the pair of fixed electrodes disposed therein, and a movable-side housing, with the movable electrode disposed therein, in the fitting and separating direction of the movable electrode and fixed electrodes. A driven pin is disposed in the fixed-side housing and a drive member is disposed in the movable-side housing in such a manner that it is prevented from moving in the fitting and separating direction of the movable electrode and fixed electrodes and it is allowed to move in a direction at right angles to the electrode fitting and separating direction. An inclined groove formed in the drive member has a base end portion open on the side edge thereof opposed to the fixed-side housing, and inclined with respect to the moving direction of the drive member. A loose fit groove is formed in the drive member and, while the fixed-side electrodes and movable electrode are fitted with each other, extends in parallel to the moving direction of the drive member from a terminal end portion of the inclined groove where the driven pin is situated. A detect means which, when the drive member is present at an energization allowable position for positioning the driven pin in the loose fit groove, allows the switching means to execute its closing operation to thereby close the main circuit, and also which, in a process where the drive member moves from the energization allowable position to an energization preventive position for positioning the driven pin in the terminal end portion of the inclined groove, allows the switching means to execute its opening operation to thereby open the main circuit.
According to a second aspect of the invention, the drive member includes a protect portion which, while the fixed electrodes and movable electrode are fitted with each other, is situated to cover the detect means.
According to a third aspect of the invention, when the drive member moves from the energization allowable position to the energization preventive position, the detect means starts the opening operation of the switching means before the drive member reaches the energization preventive position, characterized by operation resistance increasing means which, as the drive member moves to the energization prevented position side after the switching means starts the opening operation, increases the operation resistance of the drive member.
According to the first aspect of the invention, when the drive member is moved with the driven pin engaged with the base end portion of the inclined groove, the two housings approach each other while they are guided by the guide means. When the drive member reaches the energization preventive position, not only the fitting engagement between the two housings but also the fitting engagement between the fixed and movable electrodes are completed and energization is allowed between the pair of fixed electrodes. When the drive member is moved to the energization allowable position, the switching means executes its closing operation to thereby close the main circuit, so that energization between the fixed electrodes is allowed. In a process where the drive member is moved in the opposite direction from this state, the driven pin moves within the loose fit groove during the movement of the drive member from the energization allowable position to the energization preventive position. Therefore, the opening operation of the switching means is executed while the fixed and movable electrodes remain unmovable with respect to each other in the separating direction (i.e., while maintaining their mutual fitting engagement), so that the main circuit is opened.
When the drive member is moved further, the movable electrode is separated from the fixed electrodes to thereby prevent energization between the pair of fixed electrodes. In this manner, according to the first aspect of the invention, due to provision of the loose fit groove, the opening operation of the switching means for opening the main circuit can be completed while maintaining the mutual fitting engagement between the fixed and movable electrodes.
According to the second aspect of the invention, since there is formed in the drive member the protect portion for covering the detect means, the detect means can be prevented from being operated unpreparedly due to interference by external foreign bodies. Thus, the unprepared execution of the opening operation of the switching means for opening the main circuit can be prevented.
According to the third aspect of the invention, due to provision of the operation resistance increasing means, as the drive member moves to the energization preventive position side after the opening operation of the switching means starts, the operation resistance of the drive member can be increased. Thanks to this, as the time that is necessary from the start of the opening operation of the switching means to the separation of the movable electrode from the fixed electrodes, there can be secured sufficiently long time.